Harnessing solar energy to convert CO2 into high-value-added products is a viable strategy to address the energy and climate crises. Nevertheless, the low photocatalytic effectiveness continues to be a critical factor limiting its practical application. We prepared Cu(II)-doped flower-like TiO2 nano-catalysts via ammonia etching and ion exchange methods. Under solar irradiation, the Cu-doped flower-like TiO2 efficiently converted CO2 and H2O to CH4, with a yield of 47.22 μmol/g. It was found that the unique multi-level structure of Cu-doped flower-like TiO2 exposed more active Cu sites and broadened the photo-response range of the catalyst. Moreover, Cu doping facilitated the separation and migration of photogenerated electron-hole pairs on the flower-like TiO2 surface, with the formed CuO sites acting as reductive active centers to augment the photocatalytic conversion of CO2 to CH4. We demonstrate that the synergy of Cu doping and the novel titanium-based material enhances the efficiency of artificial photosynthesis for CH4, opening up fresh insights for the evolution of sustainable energy and environmental protection.